Type lever actuation arrangement in serial printers having rotating type lever magazines

ABSTRACT

In a serial printing mechanism, of the type having a rotating disc-shaped (carrousel) type lever magazine, an arrangement for swiveling up and returning the type levers selected to perform a printing movement. The displacing path and one portion of the return path, which operate on the free end of the type lever, rise out of a guide ring and extend almost to the printing point and merge one into the other, forming a single unit. The portion of the displacing path near the printing point is designed to give the type lever free ends an accleration to compensate for the bending caused by the Coriolis force, so that the letters are printed straight. Acting on extensions to the type levers is the other portion of the return path, which other portion influences the type levers so that their oscillations are damped and the type levers safely enter the normal path of rotation.

United States Patent [1 1 Galaske Dec. 10, 1974 TYPE LEVER ACTUATION 3,420,349 l/1969 Kupfmuller [97/18 x ARRANGEMENT IN SERIAL PRINTERS 3,556,277 l/1971 Galaske et a1. 197/18 3,615,000 10/1971 Galaske et al. 197/18 HAVING ROTATING TYPE LEVER 3,727,741 4/ 1973 Galaske 197/18 MAGAZINES FOREIGN PATENTS OR APPLICATIONS [75] Inventor: Folker Galaske, Pforzheim, 97

Germany 497,062 8/1954 Italy 1 /I8 [73] Assignee: International Standard Electric Primary Examiner-Ernest T. Wright, Jr.

Corporation, New York, N.Y. Attorney, Agent, or Firm-A. Donald Stolzy [22] Filed: May 22, 1972 [57] ABSTRACT [21] Appl. No.: 255,564

Related U.s. Application Data In a serial printing mechanism, of the type having a rotating disc-shaped (carrousel) type lever magazine, an arrangement for swiveling up and returning the type levers selected to perform a printing movement. The displacing path and one portion of the return path, which operate on the free end of the type lever, rise out of a guide ring and extend almost to the printing point and merge one into the other, forming a single unit. The portion of the displacing path near the printing point is designed to give the type lever free ends an accleration to compensate for the bending caused by the Coriolis force, so that the letters are printed straight. Acting on extensions to the type levers is the other portion of the return path, which other portion influences the type levers so that their oscillations are damped and the type levers safely enter the normal path of rotation.

5 i 5 ll g i efisers PATENTELUEE 1019M 3.853.211

- sum 1 or 4 PRIOR ART Fig.1

PATEHTEU 1853.21 1

' SHEEI 20F 4 PATENTEL 1 SHEET BF 4 Fig. 40

Fig. '4 b TYPE LEVER ACTUATION ARRANGEMENT IN SERIAL PRINTERS HAVING ROTATING TYPE LEVER MAGAZINES CROSS REFERENCE TO RELATED APPLICATIONS This application is filed under the provisions of 35 U.S.C. 1 19 with claim for the benefit of the filing of an application covering the same invention filed in Germany on Apr. 24, 1969, Ser. No. P 19 20 967.7. The present invention is a continuation of copending U.S. Pat. application Ser. No. 24,156 filed Mar. 31, 1970, now abandoned. The benefit of the filing date of said copending application is, therefore, hereby claimed for this application.

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to an arrangement for displacing and returning type levers intended to perform printing in serial printers. The printing unit of the serial printer comprises an assembly or magazine of type levers arranged radially in relation to an axis of rotation. A printing unit rotates at a constant speed, and the individual type levers selected for printing are deflected into a path where they rest on a guide ring with their free ends. Within a predetermined angular range, a movement of the levers is directed towards the printing point and subsequently back to the normal position by means of cam portions lying in the rotating range of said type levers.

2. Description of the Prior Art A printing mechanism of the above-mentioned type is disclosed in copending U.S. Application Ser. No. 754,578 to Folker Galaske, filed Aug. 22, 1968, now U.S. Pat. No. 3,727,741, wherein cam means leading the type levers to the printing position and back to the guide ring are disclosed. These cam means are positioned below the rotating type lever magazine. Via its free end the selected type lever is slightly lifted by an advance cam. An extension of the type lever comes into contact with an actual printing cam which leads the type lever to the printing position. After printing the rebounding type lever, through its extension, comes into contact with a positive guide consisting of two cam portions leading the type lever back to the normal path of rotation. This manner of type lever actuation has the disadvantage that adjustment is relatively difficult, the force acting on the lever extension is great, and there is no possibility of offsetting the force acting upon the free-type lever end and causing a lateral bending.

SUMMARY The present invention provides a printing mechanism which permits unobjectionable printing, i.e., of straight and equally spaced letters, at high speeds of the type carrousel. According to the invention, a device for printing on a record medium comprises disc-shaped, horizontally disposed, rotary type carrier means having a plurality of type members arranged in the plane of the disc and pivotally supported thereon and each movable from a stored position to a print position. Means are provided for rotating the carrier to urge the type members by centrifugal force and gravity into a stored position. Further, means select a type ,member from the stored position and lift it to a stationary part located above said carrier means and act on a free end of the type lever carrying the type member and permit the type members to be moved to an inwardly and upwardly located print position. The part has first means to urge the selected type member by centrifugal force and gravity into a horizontal path. Subsequent second means accelerate the type member in the direction of said record medium, so that said type member hits the record medium after a free-flight movement. Third means return the rebounding type member to the stored position by centrifugal force and gravity. Fourth BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partial sectional view of a prior art printing mechanism;

FIG. 2 is an improved printing mechanism according to the invention based on the construction of FIG. 1, in a top view limited to certain essential features;

FIG. 3 is a partial sectional view ofthe printing mechanism of FIG. 2;

FIG. 4a is a diagram showing the speed component i of the type lever orthogonally to the direction of rotation during a printing movement; and

FIG. 4b is a diagram showing the amplitudes of the bending of the free end of the type lever during the movement of FIG. 4a.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a printing unit of a serial printer with a constantly rotating type lever magazine 11, which is disposed below a printing platen 7 and is depicted in U.S. Pat. Application Ser. No. 754,578, filed Aug. 22, 1968, now U.S. Pat. No. 3,727,741. The platen 7 is stationary, and the printing unit moves therealong during printing. The rotation axis 18 of the magazine 11 is perpendicular to the longitudinal direction of the printing platen 7. A record medium R is provided around platen 7. The magazine 11 consists of two like, plate-shaped, slotted discs 11a and 1 lb, disposed in a mirror-inverted arrangement and secured to a support shank 12, which is pivotally mounted in the frame 10. The magazine 11 is driven by gearing 13, which is linked via a profiled shaft 14 with a motor (not shown). Arranged on a ring axle 15, disposed within the slotted discs 11a and 11b and concentrically around the rotation axis 18, are type levers 2 having type elements 3 thereon, the type levers 2 being supported in radial slots 17 of the discs 11a and 11b, and swivel upwardly. At rest, they are directed radially to the axis of rotation 18 and rest on the outer rim 16 of the upper slotted disc 11a due to the gravitational force. The centrifugal force, resulting from the constant rotation, partially acts in the direction of the gravitational force and causes the type levers 2 to rest securely.

Positioned about lwith respect to the printing point is a selecting station 8. The type lever 2, intended to perform printing, is swivelled from the normal path of rotation slightly upwards so as to reach a path extending above the normal path of rotation at the station 8. Following the selection, the end 2a of the type lever 2 slides along a concentric guide ring 4. In the printing zone, this guide ring 4 is provided with an upwardly extending portion 40, whereby the type lever 2 is again swiveled slightly upwards, so that its extension 2b moves into the range of a cam arrangement 9, fixed below the magazine 11. This cam arrangement 9 consists of two individual guide paths. The first, i.e., the displacing path, swivels the selected type lever 2 upwards for printing, and the second, the return path, swivels it back to the normal path of rotation afte'r printing. Each guide path consists of two parallel cams between which the extension 2b of the type lever 2 slides, thus forming positive guides.

In FIGS. 2 and 3, a type lever 2 is lifted by a selectively operable solenoid 4b onto a guide strap 4b, which guides the type lever 2 onto the top of guide ring 4. See also I1 and 23 of FIG. 2 of U.S. Pat. No. 3,615,000.

The arrangement in accordance with the invention is depicted in FIGS. 2 and 3. Instead of the cam arrangement 9 of FIG. I, a cam unit is disposed above the magazine 11 and contains two sliding paths 5a, 5b, and a cam portion 6 with a sliding path 6a is disposed below the magazine 11. The sliding path 50 forms the displacing path, and the sliding path Sb along with the sliding path 6a form the return path. The cam unit 5 is placed on the guide ring 4 in such a manner that shock-free transitions are obtained. The sliding paths 5a and 512 meet near the printing point.

The free end 2a of the type lever 2 slides along the sliding paths 5a and 512. These sliding paths 5a and 512 must therefore be shaped so that the distance between type-lever fulcrum and type-lever resting point is always about the same, independently of the angle of rotation.

Operation of the embodiment depicted in FIGS. 2 and 3 is as follows: A selecting station 8, disposed diametrically opposite the printing point, selects the type lever 2, which carries the type element 3 intended to perform printing and is swiveled'out of the normal path of rotation into a path extending thereabove (FIG. 2, position a). The free end of the type lever 2 then slides along the guide ring 4. In FIG. 2, an instantaneous position is designated 12. In the course of the further rotation of the type lever magazine II, the free end 2a of the type lever 2 reaches the sliding path 50, with the type lever 2 being swiveled upwards and thus accelerated. An instantaneous position of the type lever 2 in this zone is designated 0.

The type lever 2 then flies freely from the end of the I sliding path 5a up to the printing point, designated d,

and rebounds; its free end 2:: then reaches the sliding path 512, and a little later its extension 2b moves on to the sliding path 6a. An instantaneous position of the type lever 2 in this zone is designated e. In position f, the type lever 2 slides back to the normal path of rotation. At position g, a type lever 2 in this zone of the normal path of rotation is shown.

FIG. 4a shows the movement of the type lever 2. The speed of the type lever 2 in the swivel direction is denoted by the value v. Positive values of the speed denote a movement in the direction of the printing point, while negative values signify a movement away from the printing point. The interval shown extends from the instant of time (t at which the type lever 2 moves onto the sliding path 5a, to the instant (t at which it leaves the sliding path 5b at position f. FIG. 4b shows the bending of the type lever 2 caused thereby and is denoted by the value s.

During its displacement toward the printing point and during its subsequent return, the type lever 2 is subjected to forces which bend it sidewards. These forces are due to the Coriolis acceleration and are proportional to the speed v. which the type lever 2 moves toward and away from the printing point. Since the type lever 2 reaches its highest speed v shortly before the type element 3 impacts the printing platen 7 (instant t the effective Coriolis force and, consequently, the lateral bendingare the greatest at this instant. The result would be a laterally staggered print, and the letter would be inclined.

In order that the bending at the printing instant t;, is approximated to the value zero," the last portion of the sliding path 5a is designed so that, from the instant t, to the instant t (end of sliding path 50), the free type-lever end 2a is accelerated in such a manner that the type lever 2 stands exactly straight at the printing instant t taking into account the short free-flight period t t The printing operation may be regarded as an approximate elastic impact, with a small part of the energy being used up during printing. Therefore, the rebounding speed v of the type lever 2 is slightly lower than speed v,.

By the reversal of the direction of movement, the direction of application of the Coriolis force is reversed, also, which leads to great lateral deflections in the direction opposite the direction of application prior to printing.

In the absence of additional measures. the type lever 2 would tend toward the normal path of rotation at a speed which increases slightly only as a result of the centrifugal force and gravitational force and is indicated by the broken line (FIG. 4a), and would not reach this normal path at the instant 1 Thus, it would not be certain that the type lever 2 would move at point funder a guide strap 4a, which serves to guide the type lever 2 into the normal path of rotation. At the same time, the oscillations of the type lever 2, caused by the Coriolis force, would be damped only slightly. In FIG. 4b, this undesirable oscillation is indicated by the broken line. These oscillations would result in a high stress on the material, thus jeopardizing the safe operation.

To damp these oscillations, the sliding path 5b, acting on the free end 2a of the type lever 2, and the sliding path 6a, acting on the extension 2b at the type lever 2, are provided. The positive guide formed by these two sliding paths 5)) and 6a is designed so that the type lever 2 is accelerated during the period from the instant I,, at which the bending of the type lever 2 has reached the first maximum (FIG. 4b), to the instant t from the speed v to the speed v The resulting increase in Coriolis force, counteracting the type-lever oscillation. highly dampens the oscillation, so that the solid oscillation curve is obtained. As can be seen from FIG. 4a, the type lever 2 is slowed down to v 0 during the period 1,, I During this braking process, further damping takes place as a result of the Coriolis force. which now counteracts the oscillation again, so that the oscillation of the type lever 2 has largely died out at the instant 1 Now, a trouble-free movement into the normal path of rotation at point f is insured, in which path the free end 2a of the type lever 2 runs below the guide ring 4 (FIG. 2, point g).

It should be further understood that the foregoing disclosure relates only to preferred embodiments of the invention, and it is intended to coverall changes and modifications of the examples of the invention herein chosen for the purpose of the disclosure which do not constitute departures from the spirit and scope of the invention.

What is claimed is: 1

l. A device for printing on a record medium, the combination comprising:

disc-shaped, horizontally disposed, rotary type carrier means having a plurality of type members each formed of a lever having a free end and an extension end arranged in the plane of the type carrier means and pivotally supported thereon and each movable from a stored position to a print position; means for rotating said type carrier means to urge said type members by centrifugal force and gravity into the stored position; means to select a type member from the stored position and to lift said selected type member to a stationary part located above said type carrier means, said means to select acting on said free end of the lever carrying said selected type member, said stationary part having first'means for urging the selected type member by centrifugal force and gravity into a horizontal path;

subsequent second means for accelerating said selected type member in the direction of said record medium and for hitting the record medium after a free flight movement with said lever of said selected type member; third means for returning said selected type member to the stored position by centrifugal force and gravity; and fourth means located below said type carrier means and acting on the extension end of said lever of said selected type member in cooperation with said third means to provide a return path for said lever of said selected type member; said second means being shaped to compensate for bending of the lever free end of said selected type member, caused by a Coriolis force. 2. A device for printing according to claim 1, wherein said second and third means form a single integral part.

3. In a device for printing on a record medium, the combination comprising:

disc-shaped, horizontally disposed, rotary type carrier means having a plurality of type members each including a lever having an extension end arranged in the plane of the type carrier means and pivotally supported thereon and each movable from a stored position to a print position; means for rotating said type carrier means about a vertical axis to urge said type members by centrifugal force and gravity into the stored position; means to select a type member from the stored position and to lift said selected type member to an annular stationary part concentric with said vertical axis, said annular stationary part having a smooth, horizontal upper surface upon which said selected type member rests and slides, said annular stationary part being located above said type carrier means; a platen mounted in a fixed position relative to, but spaced vertically above, said annular stationary part in a position rotatable about a horizontal axis, said platen having an outer cylindrical surface concentric with said horizontal axis; and a cam unit fixed relative to said annular stationary part, said cam unit having first and second cam surfaces each having an upper end, said first cam surface extending from the said smooth, horizontal upper surface of said annular stationary part at one position therearound along a curve that extends circumferentially in the direction of motion of said selected type member, and extends upwardly and inwardly toward said vertical axis to said cam unit first surface upper end where the plane thereof is about normal to said horizontal axis, said second cam surface extending downwardly from the upper end of said first cam surface circumferentially in said direction of motion, and downwardly and outwardly away from said vertical axis to a position other than said one position on the said horizontal upper surface of said annular stationary part, said cam unit second surface upper end being in a plane which is about normal to said horizontal axis, said selected type member sliding over the said smooth, horizontal upper surface of said annular stationary part while rotating with said type carrier means and sliding up the said first surface of said cam unit, the said first surface of said cam unit causing said selected type member to hit said platen surface vertically, said selected type member thereafter bouncing off of said platen and engaging and sliding down said cam unit second surface back to said annular stationary part, centrifugal force and gravity causing said selected type member to slide up and in contact with said cam unit first surface and to slide down and in contact with said cam unit second surface, said cam unit first and second surface upper ends merging into a substantially vertical sharp edge spaced from said platen.

4. The invention as defined in claim 3, wherein said sharp edge is located a distance from said platen less than half the distance from said platen to said smooth, horizontal upper surface of said annular stationary part.

5. The invention as defined in claim 4, wherein said sharp edge is positioned contiguous to said platen. 

1. A device for printing on a record medium, the combination comprising: disc-shaped, horizontally disposed, rotary type carrier means having a plurality of type members each formed of a lever having a free end and an extension end arranged in the plane of the type carrier means and pivotally supported thereon and each movable from a stored position to a print position; means for rotating said type carrier means to urge said type members by centrifugal force and gravity into the stored position; means to select a type member from the stored position and to lift said selected type member to a stationary part located above said type carrier means, said means to select acting on said free end of the lever carrying said selected type member, said stationary part having first means for urging the selected type member by centrifugal force and gravity into a horizontal path; subsequent second means for accelerating said selected type member in the direction of said record medium and for hitting the record medium after a free flight movement with said lever of said selected type member; third means for returning said selected type member to the stored position by centrifugal force and gravity; and fourth means located below said type carrier means and acting on the extension end of said lever of said selected type member in cooperation with said third means to provide a return path for said lever of said selected type member; said second means being shaped to compensate for bending of the lever free end of said selected type member, caused by a Coriolis force.
 2. A device for printing according to claim 1, wherein said second and third means form a single integral part.
 3. In a device for printing on a record medium, the combination comprising: disc-shaped, horizontally disposed, rotary type carrier means having a plurality of type members each including a lever having an extension end arranged in the plane of the type carrier means and pivotally supported thereon and each movable from a stored position to a print position; means for rotating said type carrier means about a vertical axis to urge said type members by centrifugal force and gravity into the stored position; means to select a type member from the stored position and to lift said selected type member to an annular stationary part concentric with said vertical axis, said annular stationary part having a smooth, horizontal upper surface upon which said selected type member rests and slides, said annular stationary part being located above said type carrier means; a platen mounted in a fixed position relative to, but spaced vertically above, said annular stationary part in a position rotatable about a horizontal axis, said platen having an outer cylindrical surface concentric with said horizontal axis; and a cam unit fixed relative to said annular stationary part, said cam unit having first and second cam surfaces each having an upper end, said first cam surface extending from the said smooth, horizontal upper surface of said annular stationary part at one position therearound along a curve that extends circumferentially in the direction of motion of said selected type member, and extends upwardly and inwardly toward said vertical axis to said cam unit first surface upper end where the plane thereof is about normal to said horizontal axis, said second cam surface extending downwardly from the upper end of said first cam surface circumferentially in said direction of motion, and downwardly and outwardly away from said vertical axis to a position other than said one position on the said horizontal upper surface of said annular stationary part, said cam unit seconD surface upper end being in a plane which is about normal to said horizontal axis, said selected type member sliding over the said smooth, horizontal upper surface of said annular stationary part while rotating with said type carrier means and sliding up the said first surface of said cam unit, the said first surface of said cam unit causing said selected type member to hit said platen surface vertically, said selected type member thereafter bouncing off of said platen and engaging and sliding down said cam unit second surface back to said annular stationary part, centrifugal force and gravity causing said selected type member to slide up and in contact with said cam unit first surface and to slide down and in contact with said cam unit second surface, said cam unit first and second surface upper ends merging into a substantially vertical sharp edge spaced from said platen.
 4. The invention as defined in claim 3, wherein said sharp edge is located a distance from said platen less than half the distance from said platen to said smooth, horizontal upper surface of said annular stationary part.
 5. The invention as defined in claim 4, wherein said sharp edge is positioned contiguous to said platen. 